Oil seal liquid separator, and method of separating liquid therewith

ABSTRACT

A separator that uses both centrifugal force and gravity can effect the near-complete separation of liquid particles entrained in a gaseous stream having a high flow rate and velocity. The separator includes a conduit disposed in a vertical orientation, a baffle axially disposed in the conduit, a wire mesh disposed circumferentially around the baffle, and an absorbant filter disposed circumferentially around the wire mesh. The entrained liquid-containing gaseous stream enters the separator through a separator first end, and exits the separator from a separator second end as an essentially liquid-free gaseous stream. By virtue of using the baffle, mesh, and filter to effect the separation of the entrained liquid particles, the separator can effect near-complete liquid removal, yet without imposing any significant back pressure.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The invention relates generally to an apparatus for separating aliquid component from a gaseous component. The invention relates morespecifically to an apparatus for removing liquid particles entrained ina gaseous flow stream.

[0003] 2. Description of the Related Art

[0004] Gas distribution systems, such as those used for the distributionof natural gas, employ pressure relief devices known as oil seals on theoutlet side of regulator stations that feed low pressure gas systems. Bydesign, when the pressure in the gas main exceeds the static pressurehead of the oil in the oil seal, the oil is forced out of the lowerchamber of the seal and into the upper chamber as the gas continues up avent stack and exits out the top to the atmosphere. In practice,however, due to very high gas flow rates, the oil is atomized andcarried out of the vent stack along with the gas. Since the oil used istypically kerosene, an emergency spill response is then needed to removethe oil from lawns, cars, and streets in the vicinity of the stack.

[0005] Since replacement of the oil seals with a different device is acostly alternative for even a portion of an entire gas distributionsystem, a solution is needed that prevents the kerosene from exiting thevent stack. Various conventional devices for effecting aliquid-from-fluid separation are known. For example, U.S. Pat. No.735,192 describes a separator for removing oil or grease from fluids.The separator has a chamber a (disclosed as being an upright cylinder),a baffle-plate e in the form of an upright cylinder, and a drainagechamber g, which is an annular chamber surrounding the baffle-plate e.The separator uses spiral guides m to guide the fluid along the insideof the cylindrical baffle-plate e. The rotary motion imparted to thefluid by the spiral guides m tends to throw out the minute particles ofoil or grease and bring them into contact with the cylindricalbaffle-plate.

[0006] U.S. Pat. No. 2,970,669 describes a condensing filter. The filterhas a tubular body portion 12, a spiral member 16, and an absorbent wick20. The wick absorbs fractions of gas which drain to it after condensingon the walls of the spiral passageway formed by the spiral member 16 andthe tubular body portion 12. The condensed fraction drains downwardly inthe wick and is collected in the bottom of the separator.

[0007] U.S. Pat. No. 5,113,671 describes a device for separating oilfrom a gas. The separator has a housing 60 forming a peripheral wallwith an inlet at a top end of the housing for receiving an oil/gasmixture, a gas outlet formed by a conduit extending through the top endof the housing, and an oil outlet at a bottom end of the housing. Withinthe housing 60 there is a static auger 70 extending between a gas outletconduit 90 and the peripheral wall to cause the oil/gas mixture to flowin a largely circumferential path along the peripheral wall. Lining aninside surface of the housing 60 is a means for collecting andseparating oil, preferably in the form of a mesh screen 68. Thecollected oil drips from the screen to a baffle 80 having aperturestherein. The oil is received in an oil collection chamber 92 below thebaffle.

[0008] U.S. Pat. No. 5,466,384 describes a device for carrying out phaseseparation by filtration and centrifugation. The device has a chamber 1with a filtration wall 5, such as a membrane, and a helical part 8.Discharge lines 3 and 4 are provided for discharging respectively thepermeate and retentate of the mixture to be separated.

[0009] Each of the above-described patents discloses a device thatrelies upon a spiral-type element to effect at least a portion of theseparation. Various drawbacks are associated with the devices, however,including incomplete separation and the imposition of an unacceptablyhigh back pressure for use in a gas distribution system.

[0010] Therefore, a need exists for an apparatus capable of removing arelatively small volume of liquid entrained in a gaseous stream having ahigh flow rate and velocity, yet without also imposing an unacceptablyhigh back pressure to the gaseous stream.

BRIEF SUMMARY OF THE INVENTION

[0011] The present invention provides an apparatus for removing liquidparticles entrained in a gaseous flow stream. More specifically, thepresent invention provides an apparatus capable of removing a relativelysmall volume of liquid entrained in a gaseous stream having a high flowrate and velocity.

[0012] Accordingly, the present invention relates to a separatorcomprising a conduit disposed in a vertical orientation, a baffleaxially disposed in the conduit, a wire mesh disposed circumferentiallyaround the baffle, and an absorbant filter disposed circumferentiallyaround the wire mesh. The entrained liquid-containing gaseous streamenters the separator through a separator first end, and exits theseparator from a separator second end as an essentially liquid-freegaseous stream.

[0013] The invention also relates to a method of separating an entrainedliquid from a gaseous stream with the separator. The method comprisespassing the entrained liquid-containing gaseous stream through theseparator first end, imparting a rotational flow to the entrainedliquid-containing gaseous stream with the baffle, collecting therotating liquid with the wire mesh so as to separate the entrainedliquid from the gaseous stream, absorbing the collected liquid with theabsorbant filter so as to produce an essentially liquid-free gaseousstream, and passing the essentially liquid-free gaseous stream fromseparator second end.

[0014] By virtue of using both centrifugal force and gravity to effectthe separation of the entrained liquid particles, the separator caneffect near-complete liquid removal in a gaseous stream flow rate of upto 70,000 cfh, yet without the imposition of any significant backpressure. Using the baffle, mesh, and filter to effect the separation,the separator is mechanically simple, and therefore relativelyinexpensive to install and maintain.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Other features and advantages of the present invention willbecome more fully apparent from the following detailed description ofthe exemplary embodiments of the invention which are provided inconnection with the accompanying drawings.

[0016]FIG. 1 is a cross-sectional elevation view of a separatorconstructed in accordance with the present invention.

[0017]FIG. 2 illustrates details of the separator depicted in FIG. 1.

[0018]FIG. 3 is a cross-sectional elevation view of a liquid sealpressure relief system that includes the separator depicted in FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

[0019] The present invention will be understood from the exemplaryembodiments described herein.

[0020] The present invention relates to an apparatus for removing liquidparticles entrained in a gaseous flow stream. The method is particularlyuseful for the removal of a relatively small volume of liquid that isentrained in a gaseous stream having a high flow rate and velocity.

[0021]FIG. 1 is a cross-sectional elevation view of a separator 100constructed in accordance with the present invention. FIG. 2 illustratesdetails of the separator 100 depicted in FIG. 1. The separator 100comprises a conduit 110 disposed in a vertical orientation, a baffle 120axially disposed in the conduit 100, a wire mesh 130 disposedcircumferentially around the baffle 120, and an absorbant filter 140disposed circumferentially around the wire mesh 130. The entrainedliquid-containing gaseous stream enters the separator 100 throughseparator first end 101, and exits the separator 100 from separatorsecond end 102 as an essentially liquid-free gaseous stream.

[0022] The baffle 120, which in a typical embodiment has a helicalshape, is capable of imparting a rotational flow to theliquid-containing gaseous stream. By imparting a rotational flow, theheavier liquid particles are sheared from the flow stream by centrifugalforce. The sheared liquid particles are then absorbed by the absorbantfilter 140 as the dry gaseous flow exits the separator 100. Theseparator 100, therefore, uses both centrifugal force and gravity toeffect the separation of the heavy liquid particles entrained in thegaseous flow stream.

[0023] Since the baffle 120 is a flow-through baffle, no significantback pressure is developed from the added resistance to flow. In atypical embodiment, the baffle 120 has a pitch of from about 30° toabout 50°. In a more typical embodiment, the baffle 120 has a pitch ofabout 45°, which provides optimal liquid removal without a significantincrease in back pressure. For example, while a pitch of greater than45° will increase the degree of liquid separation, the added resistanceto flow increases the back pressure by about 0.5 psi for a flow rate of70,000 cubic feet per hour (“cfh”). In a typical embodiment, the baffle120 has a diameter of about 4 inches, has a thickness of from about ⅛inch to about {fraction (3/16)} inch, and is of stainless steelconstruction.

[0024] The wire mesh 130 serves to collect the rotating liquid and routeit from the gaseous stream to the absorbant filter 140. In a typicalembodiment, the wire mesh 130 is approximately {fraction (1/16)} inchwire mesh or flat expanded steel, and is of stainless steelconstruction.

[0025] The absorbant filter 140 serves to absorb the collected liquidrouted to it by the wire mesh 130. In a typical embodiment, theabsorbant filter 140 is approximately ⅛ inch thick, and comprises amaterial capable of effecting the desired degree of absorption such as,for example, polypropylene. For example, a ⅛ inch thick polypropylenefilter can absorb approximately five times its own weight, i.e., about 3lbs. or 0.45 gallons of oil.

[0026] In another embodiment, the invention relates to a liquid sealpressure relief system 300. FIG. 3 is a cross-sectional elevation viewof the liquid seal pressure relief system 300 that includes theseparator 100 depicted in FIG. 1, and a liquid seal 310.

[0027] The liquid seal 310 comprises a sealing liquid, a seal inlet 311,and a seal outlet 312, with the seal inlet 311 being in fluidcommunication with a conduit 320 for conveying a gaseous flow. Theseparator 100, which is in fluid communication with the seal outlet 312,is capable of separating the sealing liquid that is entrained in thegaseous flow during a pressure relief situation. The separator 100comprises a conduit 110 disposed in a vertical orientation. The conduit110 includes a conduit inlet 111 in fluid communication with the sealoutlet 312, and a conduit outlet 112 in fluid communication with theatmosphere for discharging the essentially liquid-free gaseous stream.

[0028] The entrained sealing liquid is typically a liquid hydrocarbon,such as, for example, kerosene, or a similar liquid capable of effectingthe requisite seal. The gaseous stream typically comprises natural gas.

[0029] The invention also relates to a method of separating an entrainedliquid from a gaseous stream with separator 100. The method comprisespassing the entrained liquid-containing gaseous stream through theseparator first end 101, imparting a rotational flow to the entrainedliquid-containing gaseous stream with the baffle 120, collecting therotating liquid with the wire mesh 130 so as to separate the entrainedliquid from the gaseous stream, absorbing the collected liquid with theabsorbant filter 140 so as to produce an essentially liquid-free gaseousstream, and passing the essentially liquid-free gaseous stream fromseparator second end 102.

[0030] In a typical embodiment, the liquid loading of the gaseous streamis approximately 0.5 gpm, or 3.125 lbs. of oil, at a gas flow rate of35,000 cfh (110 ft/sec velocity). As indicated above, the entrainedsealing liquid is typically a liquid hydrocarbon, such as, for example,kerosene. The gaseous stream typically comprises natural gas.

[0031] By virtue of using both centrifugal force and gravity to effectthe separation of the entrained liquid particles, the separator 100 caneffect near complete liquid removal. For example, tests have shown thatthe separator can effect essentially complete liquid removal in agaseous stream of up to 70,000 cfh of natural gas or air.Advantageously, no significant back pressure effect on the gasdistribution system is associated with the high degree of liquidseparation.

[0032] The present invention, therefore, provides an apparatus forremoving liquid particles entrained in a gaseous flow stream, and amethod of separating liquid therewith. By virtue of using the baffle,mesh, and filter, the separator is capable of removing a relativelysmall volume of liquid entrained in a gaseous stream having a high flowrate and velocity, yet without the imposition of any significant backpressure. The separator is mechanically simple, and therefore relativelyinexpensive to install and maintain.

[0033] Although the invention has been described and illustrated asbeing suitable for use in a natural gas distribution system, theinvention is not limited to this embodiment. Rather, the invention couldbe employed in any service requiring the removal of liquid particlesentrained in a gaseous flow stream where minimizing the resistance toflow associated with the separation is essential.

[0034] Accordingly, the above description and accompanying drawings areonly illustrative of exemplary embodiments that can achieve the featuresand advantages of the present invention. It is not intended that theinvention be limited to the embodiments shown and described in detailherein. The invention is limited only by the scope of the followingclaims.

What is claimed as new and desired to be protected by Letters Patent ofthe United States is:
 1. A separator for separating a liquid entrainedin a gaseous stream, said separator comprising: a conduit disposed in avertical orientation; a baffle axially disposed in said conduit, saidbaffle capable of imparting a rotational flow to the liquid-containinggaseous stream; a wire mesh disposed circumferentially around saidbaffle, said wire mesh capable of collecting the rotating liquid; and anabsorbant filter disposed circumferentially around said wire mesh, saidabsorbant filter capable of absorbing the collected liquid.
 2. Aseparator according to claim 1, wherein said baffle has a helical shape.3. A separator according to claim 2, wherein said baffle has a pitch offrom about 30° to about 50°.
 4. A separator according to claim 3,wherein said pitch is about 45°.
 5. A separator according to claim 1,wherein said baffle has a diameter of about 4 inches.
 6. A separatoraccording to claim 1, wherein said mesh comprises stainless steel.
 7. Aseparator according to claim 1, wherein said absorbant filter comprisespolypropylene.
 8. A liquid seal pressure relief system, said systemcomprising: i) a liquid seal comprising a sealing liquid, a seal inlet,and a seal outlet, said seal inlet being in fluid communication with aconduit for conveying a gaseous flow, and ii) a separator in fluidcommunication with said seal outlet, said separator capable ofseparating said sealing liquid that is entrained in the gaseous flowduring a pressure relief situation, said separator comprising: a conduitdisposed in a vertical orientation, said conduit comprising a conduitinlet in fluid communication with the seal outlet, and a conduit outletin fluid communication with the atmosphere; a baffle disposed axially insaid conduit, said baffle capable of imparting a rotational flow to theliquid-containing gaseous stream; a wire mesh disposed circumferentiallyaround said baffle, said wire mesh capable of collecting the rotatingliquid; and an absorbant filter disposed circumferentially around saidwire mesh, said absorbant filter capable of absorbing the collectedliquid.
 9. A system according to claim 8, wherein said entrained sealingliquid is a liquid hydrocarbon.
 10. A system according to claim 9,wherein said liquid hydrocarbon is kerosene.
 11. A system according toclaim 8, wherein said gaseous stream comprises natural gas.
 12. A methodof separating an entrained liquid from a gaseous stream with a separatorcomprising a conduit disposed in a vertical orientation, a baffledisposed in said conduit, said baffle capable of imparting a rotationalflow to said gaseous stream, a wire mesh disposed at an outercircumference of said baffle, and an absorbant filter disposedcircumferentially around said wire mesh, said method comprising: passingsaid entrained liquid-containing gaseous stream through a first end ofsaid separator; imparting a rotational flow to said entrainedliquid-containing gaseous stream; collecting said rotating liquid withthe wire mesh so as to separate the entrained liquid from the gaseousstream; absorbing said collected liquid with the absorbant filter so asto produce an essentially liquid-free gaseous stream; and passing saidessentially liquid-free gaseous stream from a second end of theseparator.
 13. A method according to claim 12, wherein said entrainedsealing liquid is a liquid hydrocarbon.
 14. A method according to claim13, wherein said liquid hydrocarbon is kerosene.
 15. A method accordingto claim 12, wherein said gaseous stream comprises natural gas.
 16. Amethod of separating an entrained liquid from a gaseous stream, saidmethod comprising: imparting a rotational flow to said entrainedliquid-containing gaseous stream; routing said rotating liquid so as toseparate the entrained liquid from the gaseous stream; and absorbingsaid routed liquid so as to produce an essentially liquid-free gaseousstream.